/* * drivers/watchdog/m54xx_wdt.c * * Watchdog driver for ColdFire MCF547x & MCF548x processors * Copyright 2010 (c) Philippe De Muyter * * Adapted from the IXP4xx watchdog driver, which carries these notices: * * Author: Deepak Saxena * * Copyright 2004 (c) MontaVista, Software, Inc. * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin * * This file is licensed under the terms of the GNU General Public * License version 2. This program is licensed "as is" without any * warranty of any kind, whether express or implied. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include static bool nowayout = WATCHDOG_NOWAYOUT; static unsigned int heartbeat = 30; /* (secs) Default is 0.5 minute */ static unsigned long wdt_status; #define WDT_IN_USE 0 #define WDT_OK_TO_CLOSE 1 static void wdt_enable(void) { unsigned int gms0; /* preserve GPIO usage, if any */ gms0 = __raw_readl(MCF_GPT_GMS0); if (gms0 & MCF_GPT_GMS_TMS_GPIO) gms0 &= (MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_GPIO_MASK | MCF_GPT_GMS_OD); else gms0 = MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_OD; __raw_writel(gms0, MCF_GPT_GMS0); __raw_writel(MCF_GPT_GCIR_PRE(heartbeat*(MCF_BUSCLK/0xffff)) | MCF_GPT_GCIR_CNT(0xffff), MCF_GPT_GCIR0); gms0 |= MCF_GPT_GMS_OCPW(0xA5) | MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE; __raw_writel(gms0, MCF_GPT_GMS0); } static void wdt_disable(void) { unsigned int gms0; /* disable watchdog */ gms0 = __raw_readl(MCF_GPT_GMS0); gms0 &= ~(MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE); __raw_writel(gms0, MCF_GPT_GMS0); } static void wdt_keepalive(void) { unsigned int gms0; gms0 = __raw_readl(MCF_GPT_GMS0); gms0 |= MCF_GPT_GMS_OCPW(0xA5); __raw_writel(gms0, MCF_GPT_GMS0); } static int m54xx_wdt_open(struct inode *inode, struct file *file) { if (test_and_set_bit(WDT_IN_USE, &wdt_status)) return -EBUSY; clear_bit(WDT_OK_TO_CLOSE, &wdt_status); wdt_enable(); return nonseekable_open(inode, file); } static ssize_t m54xx_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos) { if (len) { if (!nowayout) { size_t i; clear_bit(WDT_OK_TO_CLOSE, &wdt_status); for (i = 0; i != len; i++) { char c; if (get_user(c, data + i)) return -EFAULT; if (c == 'V') set_bit(WDT_OK_TO_CLOSE, &wdt_status); } } wdt_keepalive(); } return len; } static const struct watchdog_info ident = { .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, .identity = "Coldfire M54xx Watchdog", }; static long m54xx_wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { int ret = -ENOTTY; int time; switch (cmd) { case WDIOC_GETSUPPORT: ret = copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)) ? -EFAULT : 0; break; case WDIOC_GETSTATUS: ret = put_user(0, (int *)arg); break; case WDIOC_GETBOOTSTATUS: ret = put_user(0, (int *)arg); break; case WDIOC_KEEPALIVE: wdt_keepalive(); ret = 0; break; case WDIOC_SETTIMEOUT: ret = get_user(time, (int *)arg); if (ret) break; if (time <= 0 || time > 30) { ret = -EINVAL; break; } heartbeat = time; wdt_enable(); /* Fall through */ case WDIOC_GETTIMEOUT: ret = put_user(heartbeat, (int *)arg); break; } return ret; } static int m54xx_wdt_release(struct inode *inode, struct file *file) { if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) wdt_disable(); else { pr_crit("Device closed unexpectedly - timer will not stop\n"); wdt_keepalive(); } clear_bit(WDT_IN_USE, &wdt_status); clear_bit(WDT_OK_TO_CLOSE, &wdt_status); return 0; } static const struct file_operations m54xx_wdt_fops = { .owner = THIS_MODULE, .llseek = no_llseek, .write = m54xx_wdt_write, .unlocked_ioctl = m54xx_wdt_ioctl, .open = m54xx_wdt_open, .release = m54xx_wdt_release, }; static struct miscdevice m54xx_wdt_miscdev = { .minor = WATCHDOG_MINOR, .name = "watchdog", .fops = &m54xx_wdt_fops, }; static int __init m54xx_wdt_init(void) { if (!request_mem_region(MCF_GPT_GCIR0, 4, "Coldfire M54xx Watchdog")) { pr_warn("I/O region busy\n"); return -EBUSY; } pr_info("driver is loaded\n"); return misc_register(&m54xx_wdt_miscdev); } static void __exit m54xx_wdt_exit(void) { misc_deregister(&m54xx_wdt_miscdev); release_mem_region(MCF_GPT_GCIR0, 4); } module_init(m54xx_wdt_init); module_exit(m54xx_wdt_exit); MODULE_AUTHOR("Philippe De Muyter "); MODULE_DESCRIPTION("Coldfire M54xx Watchdog"); module_param(heartbeat, int, 0); MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 30s)"); module_param(nowayout, bool, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"); MODULE_LICENSE("GPL"); ;id=62906027091f1d02de44041524f0769f60bb9cf3'>62906027091f1d02de44041524f0769f60bb9cf3 (patch) tree6444171af03e463bb0123a392d7b91a0ae6a1f40 /tools/thermal parent6326fec1122cde256bd2a8c63f2606e08e44ce1d (diff)
mm: add PageWaiters indicating tasks are waiting for a page bit
Add a new page flag, PageWaiters, to indicate the page waitqueue has tasks waiting. This can be tested rather than testing waitqueue_active which requires another cacheline load. This bit is always set when the page has tasks on page_waitqueue(page), and is set and cleared under the waitqueue lock. It may be set when there are no tasks on the waitqueue, which will cause a harmless extra wakeup check that will clears the bit. The generic bit-waitqueue infrastructure is no longer used for pages. Instead, waitqueues are used directly with a custom key type. The generic code was not flexible enough to have PageWaiters manipulation under the waitqueue lock (which simplifies concurrency). This improves the performance of page lock intensive microbenchmarks by 2-3%. Putting two bits in the same word opens the opportunity to remove the memory barrier between clearing the lock bit and testing the waiters bit, after some work on the arch primitives (e.g., ensuring memory operand widths match and cover both bits). Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Bob Peterson <rpeterso@redhat.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Andrew Lutomirski <luto@kernel.org> Cc: Andreas Gruenbacher <agruenba@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'tools/thermal')